Myrtle Horn, 31 years old
How old are you? How old are your grandparents? Do you know how old Canada is? Zircon crystal dating the pyramids in Egypt? Do you know how old Earth is?
At present, Chemostrat can determine U-Pb ages for zircon and apatite crystals. Zircon is a robust mineral and so the crystals preserve the age at which they formed zircon crystal dating underwent high grade metamorphism. Consequently, U-Pb zircon geochronology can be employed to constrain the age of the basement rocks and in turn can help to identify sediment dispersal patterns and to correlate sandstones. If the analysed zircon crystal has not suffered either Pb loss or U gain, it will plot on the concordia line from which its age can be deduced. Sandstones frequently contain detrital zircon grains and if these grains are undisturbed and concordant, their ages provide some clue as to their provenance. Generally at least fifty grains from each sandstone sample need to be analysed in order to obtain reliable data.
What are the oldest rocks on Earth, and how did they form? The material that holds the greatest insight into these fundamental questions, because it can contain a record of some of the earliest history of the Earth, is a mineral named zircon. For example, a few grains of zircon found in the early s in a sandstone from western Australia dates back 4. Geology professors Darrell Henry of Louisiana State University and Paul Mueller of the University of Florida are expert practitioners of several techniques that can extract precise age information from zircons.
More about zircon crystal dating:
Uranium—lead datingabbreviated U—Pb datingis one of the oldest  and most refined of the radiometric dating schemes. It can be used to date rocks that formed and crystallised from about 1 million years to over 4. The method is usually applied to zircon. This mineral incorporates uranium and thorium atoms into its crystal structurebut strongly rejects lead when forming. As a result, newly-formed zircon deposits will contain no lead, meaning that any lead found in the mineral is radiogenic. Since the exact rate at which uranium decays into lead is known, the current ratio of lead to uranium in a sample of the mineral can be used to reliably determine its age. The method relies on two separate decay zircon crystal datingthe uranium series from U to Pb, with a half-life of 4. Uranium decays to lead via a series of alpha and beta decays, in which U with daughter nuclides undergo total eight alpha and six beta decays whereas U with daughters only experience seven alpha and four beta decays. The existence of two 'parallel' uranium—lead decay routes U to Pb and U to Pb leads to multiple dating techniques within the overall U—Pb system.
zircon crystal dating